Does MS-SQL answer to my problem ?

Does MS-SQL answer to my problem ?

Post by Mari-Mai Henaf » Fri, 08 May 1998 04:00:00



I have a Web application that access to (reading or
modifying) a database.

I want to duplicate my Web server and database, in
order to put it in another network platform over the
Internet. For example, one is located in Paris and
the other in Brest (another town in west of France).

People who want to access to my application will
choose the Web server that is nearest from their place.

My problem is that i want to ensure the total coherence
of the two databases : if one of the database is
modified by a client, the same modification should
be immediatly made to the other database.

Can i do this with MS-SQL and how ?
I use Javascript Server-side to connect to my database.
Does distributed transaction answer to my problem ?
Can i do distributed transactions in JavaScript ?
Or is there a way to do this without modifying the code
of my application ?

A hope someone anderstand my problem. Thank you very
much for answering...
--
Mari-Mai HENAFF

 
 
 

Does MS-SQL answer to my problem ?

Post by Ben McEw » Tue, 12 May 1998 04:00:00



Quote:> My problem is that i want to ensure the total coherence
> of the two databases : if one of the database is
> modified by a client, the same modification should
> be immediatly made to the other database.

> Can i do this with MS-SQL and how ?

There are a few possible solutions to this problem, depending on your
latency tolerance. If it's OK for your databases to be out of sync for a
few seconds or a few minutes, you could consider a replication scenario.
Two way replication is a little tricky, though, and very prone to
breakdown.

You could use distributed transactions. This solution does not require
any latency, but the transaction will fail if the servers cannot
communicate with each other.

A third solution is to roll your own updates. Write triggers to capture
all changes made during the day in a special transit table. Lots of work,
but you get the solution you want. You would have to figure out how to
deal with situations where the same row was modified in different ways on
the two servers.

Quote:> Does distributed transaction answer to my problem ?
> Can i do distributed transactions in JavaScript ?

You can perform distributed transactions using SQL. So, yes.

Quote:> Or is there a way to do this without modifying the code
> of my application ?

Replication would allow you to move data back and forth without affecting
your client app. But replication is designed to be one way- the
destination database is read-only. Two way replication is possible but
very difficult.

--
Ben McEwan, President, Geist, LLC


 
 
 

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